The complexes formed in methanol solutions of Cd(CF3SO3)(2) with selenourea (SeU) or thiourea (TU), for thiourea also in aqueous solution, were studied by combining Cd-113 NMR and X-ray absorption spectroscopy. At low temperature (similar to 200 K), distinct Cd-113 NMR signals were observed, corresponding to CdLn2+ species (n = 0-4, L = TU or SeU) in slow ligand exchange. Peak integrals were used to obtain the speciation in the methanol solutions, allowing stability constants to be estimated. For cadmium(II) complexes with thione (C=S) or selone (C=Se) groups coordinated in Cd(S/Se)O-5 or Cd(S/Se)(2)O-4 (O from MeOH or CF3SO3-) environments, the Cd-113 chemical shifts were quite similar, within 93-97 ppm and 189-193 ppm, respectively. However, the difference in the chemical shift for the Cd(SeU)(4)(2+) (578 pm) and Cd(TU)(4)(2+) (526 ppm) species, with CdSe4 and CdS4 coordination, respectively, shows less chemical shielding for the coordinated Se atoms than for S, in contrast to the common trend with increasing shielding in the following order: O > N > Se > S. In solutions dominated by mono- and tetra-thiourea/selenourea complexes, their coordination and bond distances could be evaluated by Cd K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy. At 200 K and high excess of thiourea, a minor amount (up to similar to 30%) of [Cd(TU)(5-6)](2+) species was detected by an upfield shift of the Cd-113 NMR signal (up to 423 ppm) and an amplitude reduction of the EXAFS oscillation. The amount was estimated by fitting linear combinations of simulated EXAFS spectra for [Cd(TU)(4)](2+) and [Cd(TU)(6)](2+) complexes. At room temperature, [Cd(TU)(4)](2+) was the highest complex formed, also in aqueous solution. Cd L-3-edge X-ray absorption near edge structure (XANES) spectra of cadmium(II) thiourea solutions in methanol were used to follow changes in the CdSxOy coordination. The correlations found from the current and previous studies between Cd-113 NMR chemical shifts and different Cd(II) coordination environments are generally useful for evaluating cadmium coordination to thione-containing or Se-donor ligands in biochemical systems or for monitoring speciation in solution.